Spiral matrix

data_structures/arrays/spiral_matrix.py

@@ -0,0 +1,67 @@
+class Solution:
+    def generate_matrix(self, n: int) -> list[list[int]]:
+        """Generate an n x n spiral matrix filled with numbers from 1 to n^2."""
+
+        # Create an n x n matrix filled with zeros
+        result = [[0] * n for _ in range(n)]
+
+        # Start filling numbers from 1 to n^2
+        value = 1
+
+        # Define the boundaries for rows and columns
+        row_start, row_end = 0, n - 1
+        col_start, col_end = 0, n - 1
+
+        # Continue filling the matrix layer by layer in spiral order
+        while row_start <= row_end and col_start <= col_end:
+            # Step 1: Fill the top row (left → right)
+            for i in range(col_start, col_end + 1):
+                result[row_start][i] = value  # assign the current value
+                value += 1  # move to next number
+            row_start += 1  # move top boundary down (row filled)
+
+            # Step 2: Fill the rightmost column (top → bottom)
+            for row in range(row_start, row_end + 1):
+                result[row][col_end] = value
+                value += 1
+            col_end -= 1  # move right boundary left (column filled)
+
+            # Step 3: Fill the bottom row (right → left)
+            # Only if there are rows remaining to fill
+            if row_start <= row_end:
+                for col in range(col_end, col_start - 1, -1):
+                    result[row_end][col] = value
+                    value += 1
+                row_end -= 1  # move bottom boundary up (row filled)
+
+            # Step 4: Fill the leftmost column (bottom → top)
+            # Only if there are columns remaining to fill
+            if col_start <= col_end:
+                for row in range(row_end, row_start - 1, -1):
+                    result[row][col_start] = value
+                    value += 1
+
+                col_start += 1
+
+        # return the completed spiral matrix
+        return result
+
+
+# Example usage
+if __name__ == "__main__":
+    solution = Solution()
+    n = 3  # Change this to any number, e.g., 4 or 5
+    matrix = solution.generate_matrix(n)
+
+    # Print the spiral matrix row by row
+    for row in matrix:
+        print(row)
+
+
+# Output:
+"""
+    [1, 2, 3]
+    [8, 9, 4]
+    [7, 6, 5]
+
+"""